U.S. Pat. No. 2,410,116 describes a device for a gun having a barrel coupled to the piston of a cylinder. During the recoil movement the piston compresses a gas in a storage cylinder having a floating piston acting as an energy-storage device. The stored energy is available to actuate a number of weapon functions, such as opening and closing of a breech lock, and actuation of the ejector and a plunger or other mechanism.
In the known device energy is also removed during the return movement of the barrel, which is undesirable for a number of reasons; it would be preferable to first store the recoil energy during the barrel's recoil and to either make use of the remaining energy or to convert it into heat during return of the barrel to its starting position. Since hydro-pneumatic barrel-braking and counter-recoil systems already make use of an energy-storage device, for reasons of both spatial and cost economy it should not be required to provide a further storage device; it, however, is nevertheless necessary to replenish the hydraulic medium displaced from the counter-recoil mechanism during the energy-discharge phase. It is furthermore desirable to remove only enough energy so as not to detrimentally influence the normal counter-recoil movement.